SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbb2bd704d561ce379965219718e5c0db31d8a468b0f4d4586b21bfd40bc4c91' 
  AND token = 'Kch9PSuttwCLx7EVjDpNku37mvl0tuHtZ6T1NqoFZYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}